Research On Freeway Traffic Safety Evaluation Method

The freeway mileage of China has become the first in the world.The freeway plays a vital role in improving transportation efficiency and promoting social development.However,the freeway's safety issues have always been the focus of the public and transportation management departments.Based on the research of freeway safety analysis and evaluation,the crash distribution characteristics and freeway sections' safety level can be obtained,and safety improvement countermeasures can be made scientifically.In this study,the traffic volume and crash date of Jinghu Freeway in Tianjin Section were collected and analyzed.Firstly,the AADT's variation rules with years,months and hours were studied and the traffic composition was obtained.The crash's yearly and monthly variation laws were analyzed and the crash distribution in freeway section,toll station and service area was also researched from the aspects of space and time.The Level of Safety Service(LOSS)was introduced and the LOSS division method was proposed.The safety evaluation process based on LOSS was put forward.Based on clustering method,the freeway was divided into a series of sections.The safety performance function was calibrated after analyzing the relationship between crashes and AADT of freeway sections.Then the LOSS for different AADT and crash level was determined.After that,the feasibility of applying the reliability theory to freeway safety evaluation was analyzed.The exponential model of crash duration time was established and the freeway safety reliability calculation method was determined.Then,the safety reliability of each freeway section was presented.The ARINC and MES methods were introduced to improve the safety reliability level of Jinghu Freeway in Tianjin Section and the application effect of the above two methods was comparatively analyzed.Finally,based on the Negative Binomial Model of cashes,the crash black spots were identified combined with the analysis of crash statistical distribution characteristics.After calculating the LOSS and the safety reliability,the safety evaluation methods based on LOSS and safety reliability were verified based on the crash black spot distribution.At last,the similarities and differences and the application conditions of the two safety evaluation methods were presented.